The present invention relates to an irreversible temperature indicating paint.
Irreversible temperature indicating paint changes colour at one or more known temperatures. These colour changes of the temperature indicating paint indicate the temperature to which different parts of a component or components have been subjected. The final colour of the irreversible temperature indicating paint is dependent on both the temperature it is subjected to and the time period over which it is held at a raised temperature. The irreversible temperature indicating paint is applied to a component in a test situation and subsequently analysed to determine the temperatures to which different regions of the component reached during the test. Irreversible temperature indicating paints thus produce a temperature profile over the whole surface of a component rather than discrete points, if for example thermocouples are used.
Irreversible temperature indicating paints are applied to components, for example turbine blades, turbine vanes and combustors, of gas turbine engines and the gas turbine engine is run at the gas turbine engines normal operating conditions.
One known temperature indicating paint described in our UK patent GB1103059 comprises principally lead chromate, magnesium carbonate and silica.
Another known temperature indicating paint described in our UK patent GB2204874 comprises one or more of silver, gold, platinum, palladium, copper, nickel, chromium, titanium and silicon dispersed in 10 to 70 wt % solvent and resin.
Accordingly the present invention seeks to provide a novel irreversible temperature indicating paint which has a plurality of colour changes in the temperature range 550xc2x0 C. to 1250xc2x0 C.
Accordingly the present invention provides an irreversible temperature indicating paint comprising cobalt ammonium phosphate, sodium alumino sulpho silicate, silica, alumina, toluidine red, binder and a solvent.
Preferably the binder comprises acrylic resin and silicone resin.
Preferably the irreversible temperature indicating paint comprise 15 wt % to 18 wt % cobalt ammonium phosphate, 5.0 wt % to 6.0 wt % sodium alumino sulpho silicate, 8.5 wt % to 10.5 wt % silica, 7.0 wt % to 8.5 wt % alumina, 0.5 wt % to 0.7 wt % toluidine red, 35 wt % to 43 wt % acrylic resin and 19 wt % to 23 wt % silicone resin excluding solvent.
Preferably the irreversible temperature indicating paint comprise 16 wt % to 17 wt % cobalt ammonium phosphate, 5.25 wt % to 5.75 wt % sodium alumino sulpho silicate, 9.0 wt % to 10.0 wt % silica, 7.5 wt % to 8.2 wt % alumina, 0.5 wt % to 0.7 wt % toluidine red, 37 wt % to 41 wt % acrylic resin and 20 wt % to 22 wt % silicone resin excluding solvent.
Preferably the irreversible temperature indicating paint comprise 16.4 wt % cobalt ammonium phosphate, 5.5 wt % sodium alumino sulpho silicate, 9.4 wt % silica, 7.8 wt % alumina, 0.6 wt % toluidine red, 39.1 wt % acrylic resin and 21.1 wt % silicone resin excluding solvent.
Preferably the solvent comprises a mixture of propylene glycol ethers. Preferably the solvent comprises a mixture of 80% 1-methoxy-2-propanol and 20% dipropylene glycol monomethyl ether.